Four short links: 5 September 2012

DIY Spectrometry Kit — This open hardware kit costs only $35, but has a range of more than 400-900 nanometers, and a resolution of as high as 3 nm. A spectrometer is essentially a tool to measure the colors absorbed by a material. You can construct this one yourself from a piece of a DVD-R, black paper, a VHS box, and an HD USB webcam.